1. Field of the Invention
The present invention relates to an endoscope device having pumps located in an endoscope to make the amount of gas supplied under pressure equal to that of gas sucked under pressure.
2. Description of the Related Art
Conventionally, a nozzle for cleaning a viewing window is formed in the front end portion of the endoscope and gas or fluid is jetted through the nozzle connected to air and water supply pipe systems to clean the viewing window.
In the case of the above-mentioned nozzle, however, matters such as viscous liquid and blood in the cavity of a human body enter into the nozzle and adhere there to thereby making it difficult for air and water to be supplied through the air and water supply systems when the endoscope device is being used.
There have been therefore developed two kinds of endoscope devices each having pumps capable of smoothly supplying air and water through the air and water supply pipe systems while pressure-supplying air into the nozzle to prevent the matters such as viscous liquid and blood from entering into it and also capable of sucking the air through a sucking opening to prevent excessive air from being supplied into the body cavity. One of them is of the type wherein pressure-supply and suction of air flowing through the air and water supply pipe systems are carried out by different pumps, each of which has its own drive source, to prevent the pipe systems from being jammed by the matters such as viscous liquid and blood, and the endoscope device of this type is disclosed in the Japanese Patent Disclosure No. 61-73634. The other one is of the duplex pump type wherein different pumps for carrying out the pressure-supply and suction of air are driven by a single drive means, and the endoscope device of this duplex pump type is disclosed in the Japanese Patent Disclosure No. 61-141340.
In the case where the pressure-supply and suction of air are to be carried out, it is needed that the amount of air supplied under pressure is set equal to that of air sucked to keep the pressure in the body cavity certain, that is, to prevent excessive air from being supplied into the body cavity.
In the case of the first type endoscope device wherein the pressure-supply and suction of air are conducted by different pumps, however, it is difficult to keep the amount of air supplied under pressure balanced relative to that of air sucked and even if the amount of air supplied under pressure exceeds quite a little that of air sucked, air supplied into the body cavity will become excessive when the endoscope device is used for a long time. In the case of the second type endoscope device, the amount of air supplied under pressure is balanced with that of air sucked by their own capacities of pumps. Therefore, any changes of the state in the endoscope device which have nothing to do with the pump capacities and which are seen, for example, when the amount of air sucked is decreased, that is, the effective sectional areas of the sucking, passages is reduced when any one of a plurality of medical tools is inserted deeper and deeper into the sucking pipe system, cannot be overcome. In other words, the amount of air supplied under pressure is kept certain at all times even when the amount of air sucked is decreased as described above. This causes excessive air to be supplied into the body cavity.